THE OPEN-HEARTH FURNACE.
ing apparatus is also necessary, since the course of the currents must be changed at least twice every hour. For this purpose the ordinary butterfly valve is in common use. Its simplicity, the ease with which it is manipulated, the small space it occupies, and its small first cost, have led to its general adoption and to a general urn willingness to recognize its irremediable defects. It is exposed on
FIG. VIII-H,—EEVERSING VALVES AT STEELTOST. . .
Vertical Section Through Gas Reversing Valve.
C, stack; D, main gas tube; JE, E, branch gas tube, showing valve; F,F, gas chambers; II, H. gas chamber flues to reversing valvo; I, stack reversing valve for gas; £, stack damper for gas; M, valve reversing track and buggy; N, 2V, water-cooled valve' seats: JP, P, air chambers.
one side to-the incoming gases, and on the other to the products of combustion. It will sometimes happen that these waste gases are1 red hot, and the inevitable result is a warping "of the valve or box, and a leak from the gas main into the chimney. There is no adjustment possible, and the only remedy is to replace the whole outfit.
.Fig. VIII-H shows a system of valves which has been used at Steelton with good results for a number of years, whereby the gas